CVE-2018-18445

En el kernel de Linux 4.14.x, 4.15.x, 4.16.x, 4.17.x y versiones 4.18.x anteriores a la 4.18.13, el cálculo incorrecto de enlaces numéricos en el verificador BPF permite accesos a la memoria fuera de límites debido a que adjust_scalar_min_max_vals en kernel/bpf/verifier.c gestiona de manera incorrecta los desplazamientos a la derecha de 32 bits.

A security flaw was found in the Linux kernel in the adjust_scalar_min_max_vals() function in kernel/bpf/verifier.c. A faulty computation of numeric bounds in the BPF verifier permits out-of-bounds memory accesses because this function mishandles 32-bit right shifts. A local unprivileged user cannot leverage this flaw, but as a privileged user ("root") this can lead to a system panic and a denial of service or other unspecified impact. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely.

Jann Horn discovered that the procfs file system implementation in the Linux kernel did not properly restrict the ability to inspect the kernel stack of an arbitrary task. A local attacker could use this to expose sensitive information. Jann Horn discovered that the mremap system call in the Linux kernel did not properly flush the TLB when completing, potentially leaving access to a physical page after it has been released to the page allocator. A local attacker could use this to cause a denial of service , expose sensitive information, or possibly execute arbitrary code. Various other issues were also addressed.